The present invention relates to an improved deflection plate array for electrostatic type ink-jet printers.
In the deflection plate arrays of the type described, deflection plate pairs which are equal in number to nozzles and are applied with a high voltage must be arrayed in very closely spaced apart relationship. Therefore, it is extremely hard to space them with a predetermined distance with a higher degree of dimensional tolerance and to ensure them against electrical failures. For instance, with a nozzle array consisting of 60 nozzles spaced apart from each other by 5 mm, 60 electrode pairs must be spaced apart from each other by a predetermined distance with a dimensional tolerance of .+-.0.3 mm over the width of 300 mm. In addition, a high voltage of 2 to 4 kV is applied across the deflection plate pair in the humid space with vapor evaporated from ink drops, so that a higher degree of electrical isolation between the deflection plate pairs must be established and suitable measures must be taken to ensure against electrical failures. When the deflection plate pairs are contaminated with the ink drops, they must be cleaned with water or any other suitable cleaning agent in order to prevent the degradation in printing quality. Therefore, it is very important in the design of the deflection plate array that efficient maintainability is ensured and the degradation in electrical isolation between the adjacent deflection plates will not result from the cleaning.